o The domain name extracted from a message’s RFC5322.From field is
the primary identifier in the DMARC mechanism. This identifier is
used in conjunction with the results of the underlying
authentication technologies to evaluate results under DMARC.

Experience with DMARC has revealed some issues of interoperability
with email in general that require due consideration before
deployment, particularly with configurations that can cause mail to
be rejected. These are discussed in Section 10.